This invention relates to two-dimensional nozzles for aircraft powered by a gas turbine engine and particularly to means for changing the nozzle geometry.
As is well known two-dimensional nozzles are achieving greater attention in the aircraft art particularly because of their inherent ability to integrate into aircraft shapes, their ability to deflect engine exhaust to achieve vectoring capabilities and their ability to induce super circulation about the airframe to produce additional lift.
It is further well known that optimum performance for subsonic conditions of a two-dimensional nozzle is attained by having the throat of a plug nozzle at the exit of the nozzle flaps and having the throat inclined at an angle nearly perpendicular to this plug surface. Further, it is desirable to hold the plug angle at a moderately high value, say 15.degree. thus, the throat angle contributes to gains in subsonic performance.
Equally well known to one skilled in the art is that for supersonic condition, optimum performance requires that the throat be located within the nozzle flap and inclined at an angle that is significantly larger than perpendicular to the plug. We have found that we can obtain optimum subsonic and supersonic conditions by employing a collapsing plug to size the throat area and maintain engine match. The plug dimensions allow for jet area control from dry through maximum afterburning operation at both subsonic and supersonic operation. A translating/rotating flap is used to achieve the optimum performance shape at both subsonic and supersonic flight. Flap motion is achieved by controlling the flap orientation with a contoured track which guides two rollers attached to the nozzle flap.